A comparator compares, for example, analog differential input signals and converts the signals to digital signals. A comparator includes an offset due to variations in transistors or due to asymmetrical layouts. The offset corresponds to the amount by which a threshold (difference between differential input signals that are determined by high and low levels of a digital signal) is shifted from zero. The offset adversely affects circuit operations. The threshold may be set to a value other than zero.
The following are reference documents.
[Document 1] Japanese Laid-open Patent Publication No. 2011-223553 and
[Document 2] Japanese Laid-open Patent Publication No. 2013-70156.